Using data taken with two wide-field optical cameras on the Subaru Telescope, I studied the properties of forming galaxies in ~ 800 - 3,000 million years-old universes. The galaxy samples used for this study are the largest ever obtained. The most important result is that the number density of galaxies was obtained as a function of luminosity and redshift. In addition, the origin of diffuse Lyman alpha halos around young galaxies was also identified; this is important to study the role of the matter around galaxies in galaxy evolution.

Academic Significance and Societal Importance of the Research Achievements